Chapter 13 : Why Do We Fall Ill ? - Ncert Solutions for Class 9 Biology CBSE

Biology is the study of life. It is the study of living organisms and how they interact with the environment. Biology recognizes the cell as the basic unit of life, genes as the unit of heredity and evolution as an engine which boosts the formation of new species. The study of life has helped in shaping the world. It has credible answers to why things happen in a scientific manner.

TopperLearning is a platform where students of CBSE Class 9 Biology can study various behaviours of living beings and discover interesting facts as well. Let’s learn and appreciate together the diversity of nature.

Read  more
Page / Exercise

Chapter 13 - Why Do We Fall Ill ? Excercise 178

Solution 1
Two conditions that are essential for good health are:
i. Person should be physically fit and fine.
ii. He should have good social and economic conditions.
iii. Clean environment.
 (Any two points)
Concept insight: Students should be able to recall the conditions essential for good health.
Solution 2
Two conditions essential for being disease-free are:
i. Person should take balanced diet.
ii. Personal and community hygiene.
Concept insight: Students should be able to recall the conditions essential for being disease free.
Solution 3
To some extent they are the same, because if the conditions that are essential for good health are maintained, then automatically the chances of getting disease will be minimized. But at the same time, we can say that they are different because being health or good health means physical, mental and social well-being while being disease-free means not suffering from a particular disease(s).
Concept insight: Students should be able to recall the conditions essential for good health and being disease free.

Chapter 13 - Why Do We Fall Ill ? Excercise 180

Solution 1
Common symptoms which indicate sickness are:
(i) Headache
(ii) Cough
(iii) Dysentery
If I see any one of the above symptoms, I'll immediately go the doctor.
It is because any of these symptoms can be the sign of sickness or disease.
Ignoring it, may lead to increase in the disease. The doctor will make his diagnosis and if needed, he'll get some tests done and then start medication, in case of disease.
Concept insight: Recall the symptoms of a diseased person.
Solution 2
(a) In case of jaundice, as liver does not function properly so it will have drastic long term effect on the body.    
(b) In case of lice it can remain for long time but will not have an adverse effect on the body.
(c) Acne can remain for a long time but will not affect the body adversely.
Concept insight: Difference between chronic and acute disease.

Chapter 13 - Why Do We Fall Ill ? Excercise 186

Solution 1
When we are sick the normal body functions get disturbed.
In such situation, food that is easily digestible and contains adequate nutrients are required for the speedy recovery. Thus, bland and nourishing food is given during sickness.
Concept insight: Recall the various methods of prevention.
Solution 2
Infectious diseases spread by the following means:
i. Through air: When an infected person coughs or sneezes, the microbes spread into the air and enter the body of a healthy man.  Example - common cold, T.B. (tuberculosis) pneumonia etc.
ii. Through water: The microbes from the excreta of a person suffering from a gut (alimentary canal) disease enter the body of a healthy person when he drinks polluted and contaminated water. Example - cholera.
iii. Through sexual contact: Microbial diseases like AIDS and syphilis are transmitted by sexual contact with an infected person.
iv. By vectors: Some organisms act as disease carrying agent and spread diseases. Example: female Anopheles mosquito (which spread malaria).

Concept insight: Students should remember the various means of spread of infectious diseases.

Solution 3
Precautions to reduce the incidence of infectious diseases in our school:
(i) By making available fresh and hygienic drinking water.
(ii) By preventing accumulation of water, anywhere in the school.
(iii) By keeping the toilet neat and clean.
(iv) By avoiding the consumption of uncovered food and other eatables.
(v) By using a handkerchief to cover the mouth while sneezing or coughing.
(vi) By using vaccines and immunization.
(vii) By spraying insecticides after every few months.
Concept insight: List the various precautions to prevent the spread of infectious diseases.
Solution 4
It is the process of making body immune to disease causing microbes.
In this process, vaccine is inoculated into a person to develop immunity against a particular disease. Thus immune system encounters a dead or attenuated microbe in the form of vaccine. Immune system remembers the microbe and next time kills it quickly.

Solution 5
Immunization programmes available at the health centre near our school are:
i. Vaccination against chicken pox.
ii. Vaccination against small pox.
iii. Vaccination against Hepatitis.
iv. Vaccination against tuberculosis (BCG vaccine).
v. Polio drops against polio disease.
vi. DPT (vaccination against diphtheria, pertusis and tetanus).

Out of these, the major health problems in our area are: Chicken pox, tuberculosis and hepatitis.

Concept insight: List of diseases against which vaccines are made.

Chapter 13 - Why Do We Fall Ill ? Excercise 188

Solution 1
I fell ill thrice last year and suffered from the following diseases:
i. Malaria
ii. Dysentery
iii. Viral fever

(a) Change in my habits: Now I always make conscious efforts to remain hygienic and eat covered and neat and clean food and fruits.             
(b) Change I would wish for in my surroudings: To prevent accumulation of garbage and dirty water and to keep the surroundings neat, clean and hygienic.

Solution 2
The following steps are taken by the doctors/nurses to avoid getting sick themselves:
i. Immunization.
ii. Wearing gloves and masks.
iii. Taking proteinaeous food to enhance their immunity.
iv. Taking prophylactic medicines.
v. Disposing of the blood samples, sputum etc. properly.

Concept insight: Recall the various methods of prevention.


Solution 3
After conducting a survey, I have found the following three most common diseases in my neighborhood:
i. Cough and cold
ii. Malaria
iii. Loose motions 

The preventive measures that can be taken by our local authorities to bring down the incidence of these diseases are:

i. By providing fresh, clean and uncontaminated water.

ii. By providing better and hygienic sanitary conditions in the community.

iii. By spreading information about the various preventive measures by posters, pamphlets, etc.

 Concept insight: Recall the various methods of prevention of diseases.

Solution 4
(a) The following symptoms will indicate that the baby is sick:
i. Repeated crying
ii. High body temperature
iii. Watering of eyes
iv. Watery stools
v. Redness of eyes
vi. Vomiting

(b) As far as the sickness is concerned, we can report the symptoms which we see in the baby to the doctor and can make his own diagnosis. If need be, he can also conduct some tests for verification and then advise us about the medicines and what things are to be given to the baby.    

Concept insight: Recall the various symptoms of a diseased person.


Solution 5
A person is most likely to fall sick when she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chiken-pox.                

This is because immediately after suffering from malaria, the body is still weak, as during malaria a person has loss of appetite, vomiting and fever.

Moreover, the various organ systems are also most likely not properly recovered and the immune system is also comparatively weak. So, she is likely to get infected with chicken-pox herself which can lead to serious health problems.

Concept insight: Recall the types of diseases-communicable and non communicable diseases.             


Solution 6
I will be most likely to fall sick when my friend is suffering from measles.
This is because in this condition, I will visit my friend and will be likely to get infected with measles.
Measeles is an infectious as well as an air-borne disease. When my friend will cough or sneeze, small droplets from his mouth containing microbes will mix in the air. These microbes may be present in the air I will breathe. So, the chance of getting infection will increase.
Concept insight: Recall the types of diseases-communicable and non communicable diseases.

CBSE Class 9 Biology Homework Help

Clear all your doubts instantly at our “Ask Doubt” section. Post them and we will resolve them. Get expert help and guidance at your comfort. To know the syllabus in detail, click here.

NCERT Textbooks are the rich stimulant for those students who want to score better in the CBSE examinations. By solving our papers the students have achieved a better and higher result. One of the primary objectives of creating ncert solution for class 9  is that the student gets access to an easy solution; which acts as a strong catalyst in improving the marks. We usually focus that the students doesn’t find any difficulty in understanding the concepts and can memorize them easily.